This invention relates to a hair cutting apparatus, in particular an electric hair cutting apparatus, with a shearing head comprised of a shear plate and a cutting element, with a spacer comb adapted to be seated on the shearing head for sliding contact with the skin surface to be treated, with the position of the forward edge of the cutting element being adjustable relative to the skin surface, and with a slide control for enabling and disabling the drive of the hair cutting apparatus.
In the use of hair cutting apparatus of this type, the accompanying spacer comb mounts simply by being slipped on the shearing head of the apparatus by hand. The spacer comb thus seated on the shearing head of the hair cutting apparatus is secured thereto according to the requirements of its use by means of a detent spring cooperating with a detent nose on the shearing head. However, in order to cut the hair to different lengths, it is absolutely necessary for the spacer comb to be positioned at different distances from the forward or cutting edge of the shearing head comprising a shear plate formed fast with the apparatus and an oscillating cutting element cooperating therewith. In known hair cutting apparatus, including to some extent also commercially available hair cutters, this possibility of locking the spacer comb in positions relating to the distance between the plane of its tooth-shaped supports sliding over the skin surface to be treated and the forward or cutting edge of the shearing head or the associated cutting element of the hair cutting apparatus is afforded by parallel ratchet bars formed at the outer side or sides of the shearing head housing which cooperate with lever-type detent members provided on or in the side walls of the spacer comb to operate as a ratchet gear. While such hair cutting apparatus do allow an axial displacement of the spacer comb seated on the shearing head for the purpose of varying its ratchet position in accordance with the desired length of the hair cut, it is to be considered also that such a ratchet gear on the outer wall of the body of the hair cutting apparatus, being always gripped by the user's hand, is subject to substantial wear resulting particularly from the fact that, as the spacer comb is slipped on the shearing head, at least one but mostly several or all of the outwardly projecting tight ratchet knobs are overtraveled by the inwardly projecting detent members of the spacer comb and are frictionally engaged by them in the process. The knobs on the shearing head housing are worn off or abraded by the sharp edges of the teeth of these detent members already after a relatively short period of use, so that accurate positioning of the spacer comb on the shearing head is no longer possible.
Fixing the spacer comb in place on the shearing head of the hair cutting apparatus in this manner incurs another shortcoming, that is, in order to vary the length of the cut it is necessary for the spacer comb to be gripped by two fingers, spread apart, of the hand not holding the hair cutting apparatus, and to be subsequently displaced relative to the casing of the apparatus in the slip-on or slip-off direction--depending on the desired length of the cut--until its detent member engages into the respective notch on the casing which corresponds to the selected ratchet position. This operation requires the user to abandon the position of use of the hair cutting apparatus and to seize it subsequently with his one hand to enable his other hand to adjust the spacer comb on the shearing head while keeping a close eye on the hair cutting apparatus and the spacer comb.